Process of making a solution of cellulose



Patented June 29, 1948 Fries PROCESS OF MAKING A SOLUTION OF CELLULOSE vBuurman, 'Velp, Netherlands, assignor to American Enka Co rporation,Enka, N. 0., a corporation of Delaware No Drawing. Application September30, 1946, Serial No. 700,354. .In Germany June 27, 1941 Section 1.Public Law 690, August 8, 1946 Patent expires June 2'7, 1961 i 11Claims.

The present invention relates to the manu-' iacture oi cellulosicsolutions to be employed in the production of threads, filaments, filmsand the like, and more particularly to a method of preparing alkalimetal salt solutions 04 soda celhereinafter generically referred to ascellulose.

It is known to manufacture artificial products from alkaline solutionsof sodium zincate or sodium stannate, having cellulose dissolvedtherein.

.lulose. sulphite cellulose, or cotton linters, etc.,

There ,are several methods of preparing-these solutions, e. g., thecellulose is first heated to a temperature of about 115 C. and then cutup and finally dissolvedat a temperature of about 0 C. The celulose canalso be chemically degraded by treatment with bisulphite solutions underpressure or by treatment with dilute sodium hydroxide followed by asubstantial ripening. Such degraded cellulose can then be dissolved insolutions of sodium zincate or sodium stannate by cooling the mixture to0 C. or below, and maintaining this low temperature until completedissolution 01' the cellulose fibers, whereupon the solutions are warmedup quickly to room temperature and formed into artificial products.

The present invention contemplates a process of forming cellulosicsolutions of an alkaline metal salt wherein it is unnecessary to degradethe cellulose by prolonged treatment with bisulphite solutions underpressure or by treatment with the dilute sodium hydroxide solutionfollowed by ripening,

It is a further object of the invention to inz aldehyde may be addedstage in the process. The time required for the degradation of thecellulose can also be regulated by utilizing a constant temperature atwhich the degradation takes place, or by using catalysts or by bothfixing the temperature and using a catalyst. I

' It can be readily seen that the present invention represents asubstantial simplification of the known methods of preparing thesestypes oi solutions wherein both the old and the new methods degrade thecellulose to a measured extent prior to the formation of the soution. Itis a,

substantial saving to eliminate the prolonged treatments of cellulosewith bisulphite solutions at high temperatures and under pressure, or

treatments with dilute sodium hydroxide, which in turnnecessltatesdipping, pressing and cutting up of the cellulose fibers.Incontra-distinction, the cellulose is immediately introduced into adilute alkaline solution of sodium zincate or sodium stannate whichhas-previously. been mixed with an oxidizing agent. Thus, by allowingthe pulp to age in this condition, an oxidizing degradation of thecellulose takes place.

Example 1 3350 gms. or sodium zincate solution at 25 C. containing 9.3%NaQH and 2.3% Zn. wasmixed with 330 gms. hydrogen peroxide (3%) and themixture was thoroughly stirred. 320 gms. of cut troduce normalcellulose, i. e., soda cellulose, sulphite cellulose, or cotton linters,immediately into a dilute alkaline solution of sodium zincate or sodiumstannaite containing an oxidizing agent.

In the preparation of the solution, an oxidizing agent such as hydrogenperoxide is first mixed with a dilute solution of sodium zincate orsodium stannate, and uniformly cut up cellulose is introduced withstirring. The mixture forms a thick pulp which is left standing untilthe desired degree of degradation of the cellulose is reached. Then theknown procedure is followed, namely,

up sulphite cellulose with a moisture content 01' 10% was added to thissolution under constant stirring. A thick rpulp formedwhich was leftstanding for 48 hours at 25 C., whereafter the the 'pulp is cooled downto below 0 C. with the result that the cellulose dissolves, and thesolution is then quickly warmed up to about room temperature and is inreadiness for spinning. into threads, films, and the like.

During the preparation of the solution, if any excess of oxidizing agentis present, suitable chemicals, for example, areducing agent such asformaldehyde may be added so as to prevent further degradation or thecellulose. The formpulp was cooled down to -,7 C. resulting indissolution of the cellulose. The solution was then warmed up to 16 C.and was in proper condition for spinning. Further degradation of thecellulose by an excess of hydrogen peroxide was prevented by adding 5cmof formaldehyde. The spinning solution obtained in this manner wasstable and easily spinna-ble.

Example 2 20 mg. of, nickel sulphate was added to 3650 to the solutioneither before cooling the cellulose pulp or at a later l 3 What isclaimed is:

1. A process for the manufacture of cellulosic filaments, films and thelike, which comprises adding hydrogen peroxide to a dilute alkali metalsalt solution of the class consisting of alkaline zincate and stannatesolutions, mixing cellulose with the solution to form a thick pulp,allowing the cellulose to degrade sufllciently at a constant temperatureand in the presence of nickel sulphate and then cooling the mixturebelow 0 C. whereupon the cellulose is immediately dissolved.

3. A process for the manufacture of cellulosic solutions to be used inthe production of threads, filaments, films and the like, whichcomprises adding hydrogen peroxide to a dilute alkali metal saltsolution of the class consisting of alkaline zincate and stannatesolutions, mixing cellulose with the solution to form a thick pulp,allowing the cellulose to degrade sufliciently, destroying the excesshydrogen peroxide with formaldehyde to prevent further degradation ofthe cellulose, and

then cooling the mixture below 0 C. whereupon the cellulose isimmediately dissolved.

4. A process for the manufacture of cellulosic solutions to be used inthe production of threads, filaments, films and the like, whichcomprises adding hydrogen peroxide to a dilute alkali metal saltsolution. of the class consisting of alkaline zincate and stannatesolutions, mixing cellulose with the solution to form a thick pulp,allowing the cellulose to degradesufliciently at a constant temperatureand in the presence of nickel sulphate, destroying the excess hydrogenperoxide with formaldehyde to prevent further degrade tion'of thecellulose and then cooling the mixture below 0 C. whereupon thecellulose is immediately dissolved. e

5. A process for the manufacture of cellulosic to degrade sufilcientlyat a constant temperature and in the presence of nickel sulphate.destroying the excess hydrogen peroxide with formaldehyde to preventfurther degradation of .the cellulose and then cooling the mixture below0- C. whereupon the cellulose is immediately dissolved.

8. A process for the manufacture of cellulosic solutions to be used inthe productions 0! threads, filaments, films and the like. whichcomprises adding hydrogen peroxide to a dilute sodium zincate solutionat approximately 25 C., mixing cellulose with the solution to form athick pulp, allowing the cellulose to degrade for about 48 hours at thesame temperature, cooling the mixture below 0 C. whereupon the celluloseis immediately dissolved and then raising the solution to roomtemperature in readiness for spinning.

9. A process for the manufacture of cellulosic solutions to be used inthe production of threads, filaments, films and the like, whichcomprises adding nickel sulphate and hydrogen peroxide to a dilutesodium zincate solution at approximately 25 C., mixing cellulose withthe solution to form a thick pulp. allowing the cellulose to degrade forabout 48 hours at the same temperature, cooling the mixture below 0 C.whereupon the cellulose is immediately dissolved and then raising thesolution'to room temperature in readiness for spinning.

10. A processfor the manufacture oi cellulosic solutions to be used inthe production of threads, filaments, films'and the like, whichcomprises adding hydrogen peroxide to a dilute sodium zincate solutionat approximately 25 C., mixing cellulose with the solution to form athick pulp, allowing the cellulose to degrade for about 48 hours at thesame temperature, adding suficient formaldehyde to prevent furtherdegradation of the cellulose, cooling the mixture below 0 C. whereuponthecellulose' is immediately dissolved and then raising the solution toroom temperature in readiness for spinning.

. 11. A process for the manufacture of cellulosic solutions to be usedin the production of threads, filaments, films, and the like, whichcomprises adding 'nickel' sulphate'and hydrogen peroxide solutions to beused in the production of threads,

filaments, films and the like, whichcomprises adding hydrogen peroxideto a dilute sodium 1 zincate solution, mixing cellulose with the solu-,tion toform a thick pulp, allowing the cellulose to degradesufilcientlyv at a constant temperatureand in the presence of nickelsulphate and'th'en-j cooling the mixture below. 0 C. whereuponthe, v

cellulose is immediately dissolved. V

6. 'A process for the manufacture of'cellulosic solutions to be usedin'the production of threads,v

filaments, films and the like, which comprises adding hydrogen peroxideto a dilute sodium zinc- .ate solution, mixing cellulose with thesolution to form a thick pulp, allowing the cellulose to degradesufilciently, destroying the excess hydrogen peroxide with formaldehyde,to prevent a further degradation of the cellulose, and then cooling themixture below 0 C. whereupon the cellulose is immediately dissolved. 3

7. A process for the manufacture'of cellulosic,

solutions to be used in the production of threads,

filaments, films and the like, which comprises.' adding hydrogenperoxide to a dilute sodium' zincate solution, mixing cellulose with thesoluto adilute sodium" zincate solution at approximately 2590., mixingcellulose with the solution to form a thick pulp, allowing the celluloseto demixture below- 0 Ciiwhereupon the. cellulose is immediatelydissolved andthen raising the solu- 'tionroom't m erature in. readinessfor spinning.

.1. 'N SIG V The following" references are fof record in the file ofthis patent: I

UNITED STATES PATENTS

